EXAM 1 Flashcards
What is the term for terrestrial vegetation that borders streams and rivers and is influenced by seasonal flooding?
Riparian.
What important role do mangrove swamps play in maintaining their environment?
They prevent coastal erosion.
What phenomenon explains why species in widely separated but similar biomes display similar characteristics?
Convergent evolution.
Which statement about biomes is true?
Fire is important in some biomes because it creates openings.
What is true about the structure of tropical wet forests?
Tropical forest structure consists of distinct layers that provide many different habitats.
What determines the kind of vegetation in a tropical wet forest?
The amount of rainfall.
What are the dominant herbivores in savannas?
Insects.
Which is a correct pairing of a biome and its characteristics? Tundra-
very cold winters; only the upper layer of the soil thaws during summer.
What is true about deserts and the organisms that live there?
Many desert animals are nocturnal.
Which characteristic belongs to the chaparral biome?
Plants with seeds that will germinate only after exposure to a hot fire.
Where are most of the best agricultural soils in the United States found?
In areas that were formerly temperate grasslands.
What factors help limit the growth of woody plants in temperate grasslands?
Fires and grazing by large mammals.
Which biome is characterized by large, grazing mammals?
Temperate grasslands.
Which biome is dominated by coniferous trees adapted to surviving long, harsh winters and short, wet summers?
Boreal forests.
What factor is fundamentally responsible for the character of arctic tundra soils?
Permafrost.
What best describes the interaction between fire and ecosystems?
Many kinds of plants and plant communities have adapted to frequent fires.
What is the most likely explanation for the unusual growth of ‘drunken forests’ in areas of permafrost?
Taproot formation is impossible, so trees developed shallow root beds.
In which biome would you find the greatest number of bird species based on vertical strata?
Temperate forest.
What are the major factors affecting the distribution of biomes?
Temperature and precipitation.
What information is missing from a climograph that would help predict what biome should be found?
The pattern of climatic variation including seasonal differences.
What helps produce the patchiness found in most biomes?
Disturbance.
Which biome is the largest terrestrial biome on Earth?
Boreal forests/Taiga.
Which choice correctly pairs a terrestrial biome with some of its characteristics?
Boreal forest or taiga…very cold winters, short growing season.
Which biomes are dominated by gymnosperm or conifer trees?
Taiga or boreal forests.
In which biome is vertical stratification most pronounced?
Tropical wet forests.
What could a climograph be used for?
To compare the temperature and precipitation of different biomes.
What is true about the tundra?
Permafrost prevents much water from infiltrating the soil.
Why are remnants of grassland concentrated in arid regions of North America and Central Asia?
The soil is fertile and most grassland has been converted to farmland.
Which biomes are characterized by relatively simple food webs?
Tundra and desert.
In which biome would you expect decomposers to work most rapidly and efficiently?
Tropical rain forest.
What is the aphotic zone a feature of?
The open ocean.
In which lake zone would you expect to find rooted vegetation?
Littoral.
What is a unique characteristic of estuaries?
The mixing of salt and freshwater.
What is central to coral reefs?
A symbiotic relationship with algae.
What is NOT used to categorize aquatic biomes?
Temperature.
Describe the aquatic ecosystems a salmon travels through to spawn.
Oceanic zone → neritic zone → estuary → river → stream.
During which seasons does overturn occur in a lake?
Spring and fall.
What keeps two populations of birds separate if they live on opposite sides of a peninsula?
Habitat isolation.
What hinges the formation of a new species in biological terms?
Reproductive isolation.
What describes mechanical isolation as a prezygotic barrier?
Two snails have shells that spiral in different directions.
What function does the difference in courtship songs serve in crickets?
A behavioral reproductive isolating mechanism.
What can be said about the isolating mechanisms of two hypothetical species of sparrow that migrate to different coasts?
These two species mate in different climates.
Should the light and dark forms of the peppered moth be considered separate species?
No, they can still interbreed.
What can be inferred from the hybridization of the common edible frog?
Postzygotic isolation exists between two frog species.
Which species concept distinguishes two species based on genetic exchange?
Biological.
Which species concept will you use to separate new grasshopper species without accompanying information?
Morphological.
How do two species of frogs separate if their embryos stop developing?
Reduced hybrid viability.
What is an example of reduced hybrid fertility?
The production of sterile mules.
Which postzygotic barriers prevent hybrids from forming beyond the first generations?
Hybrid breakdown.
What keeps Rocky Mountain juniper and one-seeded juniper separate?
Gametic isolation.
How are two different species most likely to evolve from one ancestral species?
Allopatrically, after the ancestral species has split into two populations.
What is an exception to the slow causes of speciation?
Polyploidy.
How do hybrid zones slow reproductive isolation?
Species with incomplete mating barriers.
When is reinforcement most likely to occur?
When hybrids have lower fitness than either parent species.
What type of reproductive isolation is represented by different courtship rituals in fruit flies?
Behavioral isolation.
Which factor would not contribute to allopatric speciation?
Gene flow between the two populations is extensive.
What is a monophyletic taxon?
It includes a common ancestor, all descendants of that ancestor, and no other organisms.
Which statement regarding classification groups is false?
Modern classification should contain polyphyletic groups.
What is true about monophyletic groups?
They include all descendants of the common ancestor of the members of the group.
When are hybrid zones likely to be narrow?
When there is strong selection against the hybrids.
Which statement about hybrid zones is false?
Broad hybrid zones typically involve hybrids that have low fitness.
What result is unlikely when two previously isolated populations come into contact?
Little reinforcement of prezygotic barriers if the hybrids are unfit.
What is an example of reinforcement in narrowmouth toads?
Mating calls that differ more in their region of sympatry.
What can you conclude from observing crickets with two wing phenotypes?
Only one genetic locus must contribute to the wing phenotype.
What illustrates phenotype variation caused by the environment?
Diet of caterpillars changes their morphology.
How many generations of random mating are required to restore Hardy-Weinberg equilibrium after migration?
1.
In a population of mustard plants at Hardy-Weinberg equilibrium, what fraction of individuals carrying the r-6 allele will be heterozygotes if the frequency is 0.2?
8/9.
Which statement about the effect of environment on gene expression is false?
The environment that can affect a gene only refers to conditions immediately surrounding the cell.
What is weight an example of?
A quantitative trait.
What must be present in a population before natural selection can act?
Genetic variation.
If the frequency of the alpha allele at locus Y6 in sea otters is 0.8, what is the expected number of alpha alleles in a population of 400 individuals?
640.
In a population of crickets with 600 individuals, what is the expected number of individuals with long wings under Hardy-Weinberg equilibrium?
384.
In a population of 200 individuals at Hardy-Weinberg equilibrium, how many heterozygous individuals are in the new population after 100 die?
48.
What is the frequency of the L allele in a population of crickets with 400 long wings, 160 intermediate, and 40 short?
0.8.
If the frequency of one allele is 0.6, what is the frequency of the other allele?
0.4.
Which statement is correct regarding cells?
All cells have the same genes.
What is the frequency of the c4 allele in a population of tree swallows with 18 homozygous, 22 heterozygous, and 10 lacking the allele?
0.58.
Under Hardy-Weinberg equilibrium, if the frequency of one allele is 0.8, what percent of the population should be heterozygotes?
0.32 - 2pq.
If an allele in a population of oysters has a frequency of 0.21, how many copies are present in a population of 600?
252.
Under Hardy–Weinberg equilibrium, if the frequency of one allele is 0.8, what percent of the population should be heterozygotes?
0.32
This is calculated using the formula 2pq.
If an allele in a population of oysters has a frequency of 0.21, how many copies of the allele are present in a population of 600 oysters?
252
What is the heterozygote frequency if the frequency of one allele is 0.7 in a population at Hardy–Weinberg equilibrium?
0.42
Which of the following could influence gene expression?
Signals from other cells, Contact from neighboring cells, Products from other genes
What is the best modern definition of evolution?
Descent with modification
Which statement about the relationship between genotype and phenotype is true?
A particular phenotype can be produced with more than one genotype
Which is not a condition for Hardy–Weinberg equilibrium?
Small population size
Which statement about variation is true?
All new alleles are the result of nucleotide variability
In Mendel’s peas, what is the term for the height of the plant?
Phenotype
In a population of marmots with an allele frequency of 80 percent for one allele, how many should be heterozygotes if at Hardy–Weinberg equilibrium?
240
In Mendel’s peas, what caused the differences between tall and short plants?
Alleles
What are the expected frequencies of red and black phenotypes in a population of flour beetles with allele frequencies of 0.5?
0.75 red, 0.25 black
What is the frequency of the L allele in a cricket population with 340 long wings, 120 intermediate-length wings, and 40 short wings?
0.8
If the frequency of b1 is 0.4 in a population of juniper trees, what can be said about the frequency of b3?
It cannot be greater than 0.6
Which of the following could not be described as a phenotype?
A sequence of nucleotides
Which population shows a heterozygote deficiency among populations A, B, and C?
Only population B
What is likely if a flowering plant species produces red, pink, or white blossoms and the frequency of A is 0.4?
The selection is favoring the red blossoms
What are the characteristics of Tundra?
Very cold winters; only the upper layer of the soil thaws during summer.
Describe environment of Boreal Forest or Taiga?
Dominated by coniferous trees adapted to surviving long, harsh winters and short, wet summers.
Describe environment of Temperate Forest?
Cold winters; hot and humid summers; year round precipitation; in North America it is dominated by deciduous trees.
What is unique about Desert ecosystems?
Has many nocturnal animals and plants with adaptations to reduce water loss.
Describe environment of Tropical Dry Forest?
Rich soil, strong seasonal variation in precipitation, consistently warm temperatures.
Describe environment of a Savanna?
Dominated by grasses and herbs, few trees; seasonal precipitation; consistently warm temperatures.
What is special about Chaparral plants and seeds?
Plants with seeds that will germinate only after exposure to a hot fire.
Biggest characteristic of Grassland?
Characterized by large, grazing mammals.
What defines Tropical Wet Forest?
Structure consists of distinct layers that provide many different habitats; decomposition occurs rapidly.
What steps are involved in the greenhouse effect?
Solar energy absorbed at Earth’s surface is radiated back into the atmosphere as heat. ( Earth absorbs the energy by the land and ocean. As the heat makes its way through the atmosphere and back out to space, greenhouse gases absorb much of it.) Greenhouse gases absorb much of this heat, trapping some of it and causing warming.
Why is solar energy per unit area more intense near the equator than near the poles?
The Earth’s tilt on its axis produces a higher intensity of sunlight towards the equator, where sunlight strikes most directly, resulting in a warmer climate. (The angle of where the sun hits near the poles is thus a lot weaker than the equator as it is farther away from the sun resulting in both areas having a rather cold climate.)
Why are the world’s major deserts concentrated at 30 degrees North and 30 degrees South?
Hadley cells form near the equator, where hot air rises and cools, causing rain. The now dry air descends around 30 degrees latitude, creating high-pressure, dry conditions that lead to deserts. The persistent high pressure and lack of moisture, these regions become extremely arid, leading to the formation of major deserts.
Define Hadley Cell.
Two circulation cells at the equator where air rises and falls at a latitude of between 30 degrees N and/or S.
Define Ferrell Cell.
The Ferrell cell is a wind pattern that occurs in the mid-latitudes, between approximately 30° and 60°.
Define Polar Cell.
Atmospheric currents that move air between 60 and 90 degrees latitude.
What causes El Nino-southern oscillation events?
El Nino events are caused by a rise in air pressure over the Indian Ocean and a fall over the central and eastern Pacific. Trade winds in the south Pacific weaken or head east, and warm water spreads eastward from the west Pacific and Indian Ocean to the east Pacific. This leads to a reversal of weather patterns across the Pacific.
How do El Nino events change the weather experienced in the western and eastern Pacific?
El Nino leads to extensive drought in the western Pacific and rainfall in the normally dry eastern Pacific, because of the reversal of the weather patterns across the Pacific.
Why do coastal continental temperatures typically fluctuate less than inland temperatures?
Coastal areas have smaller temperature variations due to the high heat capacity of nearby water bodies, which moderates the climate.
How do rain shadows cause desert formation?
Moist air rises on the windward side of a mountain, cools, and precipitates. The dry air descends on the leeward side, creating arid conditions.
DETAIL
Winds carry moist air from oceans or large bodies of water toward a mountain range.
As the air ascends, it cools and condenses, leading to heavy precipitation. This side of the mountain, called the windward side, is typically lush and green due to abundant rainfall.
After releasing its moisture on the windward side, the now-dry air descends down the leeward side of the mountain. As it descends, it warms up and expands, further reducing its ability to hold moisture. This results in very little to no precipitation, creating arid desert conditions.
Differentiate between anagenesis and cladogenesis.
Anagenesis: Evolutionary change within a single lineage over time, leading to a new species without branching.
Cladogenesis: Evolutionary branching where a single lineage splits into two or more distinct species, increasing biodiversity.
Why can species be difficult to define?
Species are difficult to define because different species concepts emphasize different criteria, such as morphology, genetics, or reproductive isolation. Some species may look identical but have significant genetic differences, while others may interbreed despite being distinct species.
Describe the morphological species concept and its shortcomings.
Defines species based on shared physical characteristics.
Shortcomings: Some species look very similar but are genetically distinct (cryptic species). Some individuals within a species can vary significantly in appearance (polymorphism). Relies on subjective judgments of which traits are important.
Describe the phylogenetic species concept and its shortcomings.
Phylogenetic Species Concept: Defines species based on their evolutionary history and genetic distinctiveness using DNA sequences.
Shortcomings: Requires extensive genetic data and advanced analysis. Difficult to determine at what point genetic differences define separate species.
Describe the biological species concept and its shortcomings.
Defines species as groups of interbreeding populations that are reproductively isolated from other such groups.
Shortcomings: Cannot be applied to extinct species. Does not work well for asexual organisms. Some species that are distinct still hybridize in nature.
Define the term polyphyletic
A group that does not include the most recent common ancestor of its members.
Describe allopatric speciation and give an example.
Occurs when a population is geographically separated, leading to divergence due to genetic drift, mutation, and selection.
Example: The formation of new species of squirrels on opposite sides of the Grand Canyon.
Describe sympatric speciation and give an example.
Sympatric Speciation: Species arise in the absence of geographical barriers. Though no geographical barrier, there is some barrier that arises to interrupt gene flow.
Example: Polyploidy in plants leading to reproductive isolation.
Give 2 examples of prezygotic isolation.
Temporal Isolation: Species reproduce at different times.
Behavioral Isolation: Differences in mating behaviors prevent interbreeding.
Give 2 examples of postzygotic isolation.
Hybrid Sterility: Hybrids are unable to produce offspring (e.g., mules).
Hybrid Breakdown: Hybrid offspring are weak or infertile over generations.
Differentiate between hybrid viability, hybrid breakdown, and hybrid sterility.
Hybrid Viability: Hybrid offspring do not survive to reproductive age.
Hybrid Breakdown: Hybrid offspring are viable and fertile but their descendants experience reduced fitness or sterility.
Hybrid Sterility: Hybrid offspring are alive but cannot reproduce (e.g., mule).
Explain the reinforcement hypothesis and give an example.
Species separated by geographical barriers produce offspring with reduced fitness in both parental habitats, reinforcing a barrier between the divergent populations.
Example: In some European flycatcher birds, hybrid offspring have lower fitness, leading to stronger mate preferences for their own species.
Define prezygotic isolation.
Prezygotic reproductive isolating mechanisms prevent gametes from two different species from fusing together and forming a zygote.
Define postzygotic isolation
Postzygotic isolation occurs when gametes of two species fuse and form a zygote, but there is no gene flow between species.
Define evolution.
The process by which populations of organisms change over time through variations in traits that are inherited across generations.
Define macroevolution.
Evolutionary changes above the level of individual populations, typically involving large-scale transformations such as the origin of new species or major adaptive radiations.
Define microevolution.
Small-scale evolutionary changes within a population over short periods of time, such as changes in allele frequencies.
Define ecology.
The scientific study of interactions between organisms and their environment, focusing on how these interactions determine the distribution and abundance of organisms.
What does the biological species concept use as the primary criterion for determining species boundaries?
Gene Flow
Which species concept distinguishes two species based on the degree of genetic exchange between their gene pools?
Biological Species
Define organismal ecology.
The study of how an organism’s structure, physiology, and behavior enable it to meet environmental challenges.
Define population ecology.
The study of populations, which are groups of individuals of the same species living in an area.
Define community ecology.
The study of communities, which are groups of populations of different species in an area.
Define ecosystem ecology.
The study of ecosystems, which are communities of organisms and their interactions with the physical environment.
Define landscape ecology.
The study of landscapes (or seascapes), which are mosaics of connected ecosystems.
Define biosphere.
The global ecosystem, the sum of all the planet’s ecosystems and landscapes.
Define global ecology.
Examines the influence of energy and materials on organisms across the biosphere.
What are the 3 main jobs of coral reefs?
Deliver oxygen, Deliver nutrients, Remove waste.
Define estuary.
An estuary is a transition area between a river and the ocean.
Define thermocline.
The thermocline is a temperature boundary that separates warm water from cold water.
Define turnover.
Turnover refers to the seasonal mixing of water in lakes.
What are aquatic biomes characterized by?
Water depth, water flow, and salinity.
Define convergent evolution.
Convergent evolution refers to the phenomenon where similar characteristics arise in unrelated species in different biomes.
What do climography plots depict?
The amount of precipitation and temperature of a given biome.
How are biomes defined?
By their annual patterns of temperature and precipitation.
Define biome.
A biome is a geographic region that contains communities composed of organisms with similar adaptations.
Define climate vs. weather.
Weather is the short-term state of the atmosphere. Climate is the long-term pattern of weather.
Why is convergent evolution common in biomes?
Similar environmental pressures can lead to the development of similar adaptations in species from different evolutionary lineages.
How are biomes classified?
By their dominant vegetation type.
When creating a climate diagram, which variable is graphed on the x-axis?
Months.
What study/approach of ecology involves studying a stream at various times of the year?
Community.
What biome occurs in equatorial regions without a distinct dry season?
Rainforest.
What biome is maintained by seasonal drought, grazing, and fires?
Savanna.
Where is the lowest average annual temperature found?
Tundra.
What biome is dominated by trees with broad, thin leaves?
Deciduous forest.
What biome receives sparse rainfall and contains plants with small, finely divided leaves?
Desert.
Define homologous traits.
Similar between organisms that evolved from the same common ancestor.
Define analogous traits.
Superficially similar traits, usually because of a similarity in usage.
How can changes in gene sequence lead to phenotypic change?
Changes in gene sequences can lead to changes in the proteins encoded by the genes.
Explain the importance of heritable variation for evolution.
Heritable variation provides the raw material upon which natural selection can act.
Define phenotypic plasticity and give an example.
Phenotypic plasticity refers to the ability of an organism to express different phenotypes in response to environmental changes.
Example: Some species of reptiles have their sex determined by temperature.
Explain how epigenetics could influence phenotype.
Epigenetics involves changes in gene expression that do not alter the underlying DNA sequence.
Give an example of an environmentally determined phenotype.
The color of flamingos, influenced by the carotenoid pigments in their diet.
Describe genotype by environment interactions.
Genotype by environment interactions occur when different genotypes respond differently to changes in the environment.
Explain how heritability is calculated.
Heritability is calculated using offspring-parent regressions.
List and define the evolutionary mechanisms.
The evolutionary mechanisms that cause allele frequencies to change are: Mutation, Natural selection, Gene flow, Genetic drift.
List the assumptions of the Hardy-Weinberg Equilibrium.
The assumptions are: The population is large, Mating is random, There is no mutation, There is no migration, There is no natural selection.
Determine if a population is in Hardy-Weinberg Equilibrium.
Calculate the expected genotype frequencies using the Hardy-Weinberg equation and compare them to the observed frequencies.
Define population genetics.
Population genetics is a branch of genetics that studies the genetic composition of populations.
In order for a trait to evolve, it must be what?
Heritable.
Define reaction norm.
A reaction norm is the range of phenotypes produced by a genotype in response to changes in environmental conditions.
What is it called when you lose a trait and gain it back?
Atavism.
Define reversal.
Reversal refers to the loss of derived traits in a lineage, resulting in a return to the ancestral condition.
Define Paraphyletic groups
A group that includes a common ancestor but not all of its descendants.
Define Monophyletic
All members of a taxonomic group share the same common ancestor.
What type of selection is most likely found in a large lake with a high density of three-spined stickleback fish?
Disruptive Selection
Which condition allows gene frequencies to change by chance?
Small Populations
What condition will most likely lead to more disruptive selection in a sparrow population that eats medium-sized seeds?
More seeds that are either considerably smaller or considerably larger than average, with fewer that are of intermediate size
What conclusion can be drawn from a large population of laboratory animals where 25% display a recessive trait after several generations?
The two phenotypes are about equally adaptive under laboratory conditions
What is likely to occur if a new virus in swine has a Tamiflu-resistance gene and is introduced to an environment lacking Tamiflu?
If the Tamiflu-resistance gene involves a cost, it will experience directional selection leading to reduction in its frequency.
What is the example of frequency dependent selection in sexual species?
Members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex.
How is natural selection best described?
The differential survival and reproduction of individuals
What type of selection is indicated by a population of spiders where the average eye size does not change but the range of variation decreases?
Stabilizing
What is the most plausible reason for the lack of evolution in a beetle population with little evolutionary change for size?
There is no difference in survival or reproduction among beetles of different sizes.
What understanding do modern biologists have that Darwin did not?
The detail of genetic inheritance
What type of selection do goldenrod gall-flies experience due to predation by wasps and birds?
Stabilizing Selection
What type of selection is indicated by the elaborate plumage of male birds of paradise due to females mating preferentially with males that display the most impressive feathers?
Directional and or Sexual
What is the net effect of exposure to malaria on sickle-cell allele frequency?
Increasing sickle cell frequency
Which statement about Darwin is true?
He had a keen interest in Geology
Variation at a locus in a population of grasshoppers appears to be maintained by either heterozygote advantage or frequency-dependent selection.
What observation would be consistent with heterozygote advantage in grasshoppers?
Both homozygotes are less fertile than the heterozygote.
What is the main difference between Darwin and Wallace regarding their contributions to evolutionary biology?
Darwin presented more extensive evidence in support of evolution than Wallace.
What type of selection is operating when male earwigs that are DD have greater mating success?
Directional
What is the likely result of very large clutch sizes in bird species?
This is an example of a trade-off, and selection should favor intermediate-sized clutches.
What type of selection would occur if intermediate-sized individuals are less able to find food?
Disruptive selection for body size
What type of selection is a copepod population experiencing if larger individuals are preferred by fish predators?
Stabilizing; if the fish predators disappear, it would most likely experience Directional selection.
What example best fits the term ‘artificial selection’?
Researchers breeding yeasts that can withstand high concentrations of ethanol.
What condition will most likely lead to more directional selection in a sparrow population eating medium-sized seeds?
More seeds that are somewhat larger than average and fewer that are smaller than average
Which mode(s) of selection result(s) in a decrease in variation?
Both directional and stabilizing selection
What is the example of artificial selection observed by Edith Smith with Buckeye butterflies?
Breeding the bluest butterflies together to produce vibrant blue butterflies for use in wedding displays.
What circumstance indicates evolution has taken place but not adaptation?
A population of rats that landed on an island three generations ago has different frequencies of alleles compared to the mainland population due to the bottleneck.
Why might conditions like sickle cell anemia and cystic fibrosis persist in populations?
Sickle cell anemia and cystic fibrosis persist in populations due to heterozygote advantage. Heterozygotes for sickle cell are resistant to malaria, while heterozygotes for cystic fibrosis are more resistant to diseases like TB and cholera.
What is an example of stabilizing selection in humans?
An average birth weight of around 7lbs in humans.
What did Lamarck believe about traits?
Traits are acquired through use or via disuse.
